Bump next from 15.5.7 to 16.1.5

Bumps [next](https://github.com/vercel/next.js) from 15.5.7 to 16.1.5.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.7...v16.1.5)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 16.1.5
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

frontend/package.json

@@ -2,7 +2,7 @@
   "dependencies": {
     "@aws-amplify/adapter-nextjs": "^1.6.9",
     "aws-amplify": "^6.15.6",
-    "next": "^15.5.7",
+    "next": "^16.1.5",
     "react": "19.2.0",
     "react-dom": "19.2.0"
   },